A wind power plant usually has a plurality of wind turbines for converting wind energy to electricity. Additionally, the wind power plant may comprise a power plant controller (PPC) and/or some sort of reactive power compensation equipment, such as static synchronous compensators (STATCOMs) or switch/switched capacitors, or others.
To supply electricity to the electricity end users, the wind power plant is connected to a power grid. However, before the wind power plant can be connected to a power grid, the wind power plant has to meet the requirements of electrical performance of the wind power plant specified by grid codes. One requirement is an initial response time of the wind power plant. Generally, the wind power plant has a wind power plant controller which monitors a power grid voltage and compares the power grid voltage with an external setpoint. A difference between the actual power grid voltage and the external setpoint (e.g. an error signal) is used to calculate a command for reactive power production for the wind power plant. This command is sent from the wind power plant controller to the individual wind turbines which in turn will respond (e.g. produce more or less power in order to adjust the power grid voltage) upon receiving the command. The error signal may be caused by a change in the actual power grid voltage or a change in the external setpoint.
It is an object of the present invention to improve the voltage control of a wind power plant.